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ABSTRACT
Theou, O, Gareth, JR, and Brown, LE Effect of rest interval on strength recovery in young and old women. J Strength Cond Res 22(6): 1876-1881, 2008-This study compares the effects of rest intervals on isokinetic muscle torque recovery between sets of a knee extensor and flexor exercise protocol in physically active younger and older women. Twenty young (22.4 ± 1.7 years) and 16 older (70.7 ± 4.3 years) women performed three sets of eight maximum repetitions of knee extension/flexion at 60°.s^sup -1^. The rest interval between sets was 15, 30, and 60 seconds and was randomly assigned across three testing days. No significant interaction of rest by set by age group was observed. There was a significant decline in mean knee extensor torque when 15- and 30-second rest intervals were used between sets, but not when a 60-second rest interval was applied for both the young and the old women. No significant decline for mean knee flexor torque was observed in the older women when a 30-second rest interval was used, whereas a longer 60-second rest interval was required in younger women. Active younger and older women require similar rest intervals between sets of a knee extensor exercise (60 seconds) for complete recovery. However, older women recovered faster (30 seconds) than younger women (60 seconds) between sets of a knee flexor exercise. The exercise-to-rest ratio for knee extensors was similar for young and old women (1:2). Old women required only a 1:1 exercise-to-rest ratio for knee flexor recovery, whereas younger women required a longer 1:2 exercise-to-rest ratio. The results of the present study are specific to isokinetic testing and training and are more applicable in rehabilitation and research settings. Practitioners should consider age and gender when prescribing rest intervals between sets.
KEY WORDS muscle fatigue, exercise-to-rest ratio, aging, resistance exercise, isokinetic
INTRODUCTION
Isokinetic testing has become a popular method to assess dynamic muscle strength in botii clinical and research settings (7,17,18,20,27) and is widely used for injury rehabilitation and measurements of muscle torque, work, power, and endurance (3,8). The exerciseto-rest ratio is a critical variable for isokinetic testing and training, and die rest period length needs to be selected on the basis of the individual's goals to maximize the benefits of a training...